Hi,I can't reproduce the issue, or maybe I don't understand it.If I set the Taskbar button to Frequency, it only affects the progress bar of the Taskbara button. It has nothing to do with the Notification Area colors.

1. Make sure that you are using the latest Core Temp version. Some earlier versions had a couple of bugs in the notification area department.2. Close Core Temp, delete 'Core Temp.ini', restart Core Temp. See if that lets you select yellow bg for frequency without affecting Core 0. On my system this doesn't happen.